Folding machine and method



D60 17, i929. A. R. RlDDERsTRoM FOLDING MACHINE AND METHOD originl FiledJune 24. 1921 3 Sheets-Sheet [Homey DeC- 17, l929- A. R. RIDDERSTROMFOLDING MACHINE AND METHOD Original Filed June 24. 1921 3 Sheets-Sheet 2Dec. 17, 1929. A. R. RIDDERSTROM A 1,740,409

` FOLDING MACHINE AND METHODv Original Filed June 24. 1921 5Sheets-Sheet. 3

WL Mii/1a( Patented Dec. 17, 1929 UNITED STATES PATENT OFFICE ANDREW R.RIDDERSTROM, OF NAHANT, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS,TO UNITED SHOE MACHINERY CORPORATION, OF PATERISON, NEW JERSEY, ACORljORATION OF NEW JERSEY FOLDING MACHINE AND METHOD Application led.Tune 24, 1921, Serial No. 480,177. Renewed May 31, 1928.

The present invention relates to folding methods and machines, and moreparticularly to methods of and machines for folding a binding strip thathas previously been sevved to the upper. This folding operation may beperformed in a folding machine, through which the upper is progressivelyadvanced or fed to the folding instrumentalities. In the interest ofeconomy, such folding machines should be operated at high speed. It iseasy enough to operate a properly designed folding machine at high speedwhen folding along straight portions of the stock. Difficulties occur,however, at the curved p ortions, particularly those portions that areAvery .sharply curved. At such portions, the stock must be fed throughthe machine either at a lower speed or by shorter feed strokes.

An object of the present invention, therefore, is to' provide in afolding machine having a feed mechanism, an improved, autof p maticallyacting mechanism for varying the feed strokes. The range of the feedStrokes may be varied automatically from zerol to a maximum. The zero,or substantially zero, range is particularly valuable at sharp, convexcurves, for the stock is not then fed forward at all,-or is fed but verylittle,but is simply turned in' its plane by the operator while theother operating instrumentalties perform the folding.

Another object of the invention is to provide an improved method offolding shoe uppers and similar articles. y

If the binding strip is to lie smoothly at the curved margins of theupper, particularly the concave margins, it must be snipped at thoseportions, as is well known. It is among the objects ofthe presentinvention to provide an improved machine for effecting this snipping,and a feature of the invention conteniplates employing a separator thatseparates the binding strip from the upper as a' stationary member ofthesnipping mechanism.

A further object of the invention is to provide, in a folding machine, asnipping knife that is automatically disconnected from its actuatingshaft at the end of a predetermined, limited, rotative movement of thelatter.

Vith the above and other objects in view, as will become clear in thecourse of the following description, the invention consists of theimproved method and machine an ernbodiment of which is hereinafterdescribed. illustrated in the accompanying drawings, and defined in theappended claims.

In the drawings:

Figure 1 is an `elevation, partly in longitudinal section, upon areduced scale, of a machine embodying the present invention, the treadlemechanism beingv shown detached and upon a further reduced scale;

Figure 2 is a section similar to Figure 3, showing the parts occupyingrelatively di iferent positions;

Figure 3 is a section taken substantially upon the line 8-3 of Figure l,looking in the direction of the arrows;

Figure :t is a view of a treadle, showingV treadle rods looselyconnected thereto;

Figure 5 is a section taken substantially upon the line 545 of Figure 2,looking in the direction of the arrows;

Figure 6 is a section taken upon the line 6-6 of Figure 2, looking inthe direction of the arrows;

Figure 7 is a perspective view of a preferred combined separator andstationary knife, shown in conjunction with the movablel knife;

Figure 8 is an enlarged viewl of a portion of the same;

Figure 9 is a perspective view of the upper forward part of the machine,parts being broken away for clearness;

Figure 10 is an enlarged detail plan, illustrating the operation offolding a binding strip attached to a shoe upper;

Figure 11 is a vertical section taken substantially upon the line 11-.11of Figure 10;

5 Figure 12 is a section of a shoe upper, showing the folding action at*a sharp convex curve.

The invention is illustrated in the accompanying drawings in connectionwith t-he folding of a binding strip 2, of cloth, silk and the like,around the edge 4 of a sheet of leather or other material 6, such as aboot or shoe upper. An edge 8 of thebinding strip is stitched at 12 to aface 10 of the shoe upper along the edge 4, so that the sheet and thestrip extend at an angle to each otherfrom the secured-together edges 4and 8. 1t will be understood that the invention is l equally applicableto other articles than that which is herein chosen for purposes v3'5 ofillustration, and the elem-ents of the article need not necessarily beof the relative dimensions shown. Y

The shoe upper is initially placed in the machine upon a platform orsupport 24, Figure 9, with the face 10 of the upper in contact .with thesupport. VAn end of the free or unsecured edge 26 of the lstrip 2 isinitially moved across and around the securedtogether edges 4 and 8, andinto the space between a feed point 30 and'a plow 32 that stands upintegrally from a plate 34. YThe machine being set into operation,successive portions of the unsecured edge or portion of the strip 2 nearthe stitches 12 are intermittently w-iped tightiy across the Isecured--together edges 4 and 8, or away from the stitches, as shown moreparticularly at 36, Figure 13, by the combined action of a wiper 38' anda retainer 246 that pressesgdown heavily at this time upon the upperdirectly opposite to the point of actionof the wiper. 1t is veryimportant to the subsequent operation that the strip be wiped verytightly. In order to enable the wiper 38 to operate, the ystrip 2 isprogressively moved lightly or loosely by the operators fingers from theposition of Fig. 12 more or less into the plane of the shoe-upper Isheet6, as the shoe upper is fed forward through the machine. Thesuccessively wiped portions are initially folded A v'ention..

-described here.

a somewhat greater range of diagonal movearound the secured-togetheredges 4 and 8 by the plow, during its backward movement with the feedelements, as described in the said Letters Patent No. 1,527,396. Theplow is of gradual-incline construction in the line of feed, asillustrated more particularly in Fig. 10, to effect a gradual folding ofthe striparound the edge of the sheet. The plowfolded portions of thestrip are intermittently gripped between the feed point and the plow 32,becoming thereby pulled tightly. rlhe intermittent wiping, and foldingand gripping operations are performed upon the successive portions ofthe strip alternately during suc-A cessive pauses in the feed. Theplow-folded portions are advanced by the feed point and a cooperatingfeed block 41, that is carried integrally with the plow 32 upon theplate 34,

to a combined folder and fold presser 42.-

rl`he fold presser 42 folds the plow-folded 4portions of the lstripfurther-and presses them down against the other face 16 of the sheet, asshown in'Fig. 18. The preferred fold'presser 42 is described in the saidLetters. Patent and in Letters PatentNo. 1,527,395,

also l.granted :February 24, 1925. These opnot fully disclosed herein,because unnecessaryto an understanding of the present in- 'lhe preferredwiper 38 is also fully described in the said Letters Patent No.1,527,396, and need not, therefore, be further A modilied wiper, havingment out of the plane of the stock, is disclosed in a copendingapplication, `Serial No. 633.120, filed April 19, 1923.

The binding Strip is maintained in aide-d position upon the face 16 ofthe leather by previously applied, wet cement. A machine. adapted foruse with dry-cemented strips isdisclosed'in a copending application,Serial No. 605,374, filed December'7, 1922. If the initially folded wetcemented strip were permitted to Contact with the edges 4 and 8 beforeit has become tightly gripped and pulled tight by the combined action ofthe feed point and the plow, it would not be possible to pull the striptight, and the resulting fold would be defective. A separator 143 istherefore provided, near the diagonally cut-away, front portion of the.plow, to maintain the strip separated from the raw edges 4 and 8 untilafter the feed point and the plow have had an opportunity to pull thestrip tight. By reason of theY diagonally cut-away, or inclined c011-struction, a more gradual folding effect is obtained than would bepossible if the plow were not so inclined. The separator 143 may, i

stud 147.

if desired, extend forward across the plow to a point very close to thefold presser, but the construction shown more particularly in Figures 7,8 and 10 is found to be sufficient,in practice. The separator is carriedupon the end of an arm 145 that is pivoted about a stud 147 mounted onthe upper end of the bracket 61. rlhe separator isfioating, beingmaintained yieldingly in the illustrated, active position by a spring149, but it may be pivotally lifted out of the way, when desired, bypressing down upon a linger piece 151 integral with the arm 145 upon theother side of the. pivotal The separator 143 is constituted of resilientor yielding material, so that it may float in the space between theedges 4 and 8 au d the partly turned binding strip. rlhis is of greatadvantage when turning sharp convex corners, as the separator floatswith the stock while the material is turned in its plane at sharpcurves. If the separator could not yield at such places, it would pullthe stock away from the fold presser, resulting in poor folding. As theseparator yields, however, 25l

the fold presser is enabled to maintain its grip upon the work. ln thespecific construction shown, the separator comprises a spring lyingloosely ina groove 263 of the arm 145 and extending through an opening255. One end (not shown) of the spring separator-143 is hooked orotherwise secured to the under side of the arm 145.

rl`he separator is maintained in placebetween the binding strip and theraw edges 4 and 8 until the forward movement of the feed elements,carrying the stock with them, causes the separator to be left behind.The binding strip cannot, therefore, stick to the edges 4 and 8 before.it has been properly folded over.

Sometimes, it is desired to have the stock rest upon a table 176, shownin Figure 1 as supported by adjustable abutments 178, and

encircling the platform or support 24 and the operating mechanisms. Uponother occasions, this table may be pivotally moved out of the way abouta pivotal axis 171.

The retainer 246 presses down upon the stock and operates asrlescribedin the said Letters Patent No. 1,527,396.

The retainer-operating mechanism is fully illustrated and described in acopending application Serial No. 407,336, filed September 1 1920.

7An arm 250 of somewhat greater length than that of the retainer isprovided for the purpose of contacting with a stationary part of themachine at 252, so that when the machine runs idly. the retainer 246'cannot become lowered into contact with the wiper and, b v hammeringaway at the wiper, injure it. The point 252 is in the present instanceshown on the upper face of a. bracket 61. The bracket 61 is verticallyadjustable, as described in the said Letters Patent No. `1,527 ,396,through of the bracket. Compensating adjustment for the arm 250 istherefore necessary. It is,

furthermore, frequently desired to adjust the arm 250 relative to theretainer 246 to accommodate stock of different thickness. A very simpleadjustment is illustrated in Figure 11. The retainerl arm 250 is bent at253, and is* provided on either side of the bend with countersunkopenings 255', adapted to receive the heads of screws 257. The screws257 may be threaded into screw-threaded openings 259 upon the retainerarm 153. To adjust the arm 250, t-he screws 257 are loosened, the arm250 is adjusted to the desired position upon the lretainer 153, and thescrews 257 are then tightened.

Before the machine is started, it is desirable to raise the feed pointfrom the feed block to permit the insertion of the upper therebetween. Apreferred construction for raising the feed point is illustrated anddescribed in the said Letters Patent No. 1,527,396, and comprises anintermediately pivoted lever 307 that is normally maintained in theillustrated position (Fig. 1) by a spring 310 coiled about a rod 312. Atreadle 313, acting upon a link 316, is adapted to actuate the lever 307so as to cause the raising of the feed point 30, as illustrated anddescribed in the said Letters Patent No. 1,527,396. The feed point, inturn, raises the retainer by engaging the under side of the arm 250.

ln order that the binding strip may lie smoothly upon the face 16 oftheleather sheet at concave portions of the work, as shown at 174, Figure10. Such snipping is performed in the present machine, after the wiperand t-he plow have acted, and just prior to the folding operation, whilethe strip is partly turned against the separator, as will be understoodfrom Figure 7. A sharp-pointed knife 352 is caused to pierce or puncturethe strip at an intermediate or interior point, while the stock isclamped down, and the knife is then swung outward, between the legs 353of the separator support, towards the free edge 26 of the'strip, to snipthe margin of the strip from the interior point outward to the edge.rlhe knife is mounted upon the end of a knife-carrying bar 354 that ispivoted at 356 to one end ofa link 358 the other end of which is pivotedabout the studv 147 between prongs 360 at the upper end of the bracket61. Adjustment of the bracket 61 has no appreciable effect upony theoperation of the knife. The other end of the knife-carrying bar 354 isprovided with a circular opening 362 eccentrically disposed to anopening 364 in a gear 366, thus constituting an eccentric strap. rllhegear 366 meshes with the gear 154 upon the ydriving shaft, and so iscontinuously after folding, it is desirable to snip the strip driventherefrom. The .knife bar 354 is adapted to be clutched to the gear 366by a novel clutching mechanism that will now be described.

For convenience of manufacture, the gear 366 is formed of two parts, onethe gear proper, which is annular in shape, as will be understood fromFigures 2, 3 and 5, and the other -a body portion 368 to which theannular gear is secured by screws or bolts 370. The body portion 368 isintegrally provided with a hollow shaft 372 mounted in a bearing 374 lof the machine frame, and the hollow shaft is held in place within thelbearing by a screw 376 threaded into a screw-threaded opening 378 of thehollow shaft and the head of which engages a washer 380. The hollowshaft is continuously rotated within the bearing 374 because thusrigidly secured to the annular4 gear. A second hollow shaft l382 isrotatably mounted within the hollow of the shaftv 372, and is heldagainst longitudinal movement therein by a pin 384 extending throughopenings 386 at opposite sides of the hollow shaft 372 and betweenannular shoulders 388 of an annular groove 390 formed upon the hollow lA shaft 382. A shaft 392 islongitudinally slidably` mounted within thehollow of the shaft 382, but is prevented from rotating therein by a pin394 fixed to the Ishaft 392 and extending into a longitudinally disposedopening 396 of the hollow shaft 382. A coil compression spring v398within the hollow of the shaft 382 acts upon the inner end ofthe shaft'392 to press it normally outward. The shaft 392 is adapted to bepressed inward. against the 1 force of the spring by a lever 400.' Thegear 366 is provided with a plurality of openings 402. As the.- gear 366contiiiuously rotates, one of these openings will become rotated intoline with thepin 394, which will be forced by the lever 400 into thesaid opening 402. The pin will thereupon act as a clutching elementagainst a side wall of the said opening 402 to clutch the shaft 392 and,through it, the holtated thereby.

, plate 408, and a disk 416secured to the eccentric by screws 418,engaging the outer face of 4the plate 408. At the end of one completerevolution, or any other desired predetermined movement of the gear366,an opening 420, Figure 6,.of the knife-carrying bar 354 will registerwith the said opening'402 of the gear, whereupon, assuming that thelever 400 has become moved out of the way, the spring 398 will force theshaft 392 into its The lever 400 is under the control of theoperator,gso that the knife-carrying bar may be rendered effective orineffective, at4 will. The lever 400 is shown intermediately pivotedabout the same pivotal point 171 about which the table 1 76 is pivoted,and its other end is hooked at 422 to one end of treadle rod 424 theother end of which is loosely connected to the other end ofthe treadle313. The treadle 313 is adapted'normally to occupy an intermediateposition, as shown in Figure 4, in which it is ineffective. Upon theoperator moving the treadle in one direction, the treadle rod 316 willact upon theilever 307 to actuate the feed point, as above described.Actuation of the 4treadle 313 in the other direction, beyond theintermediate, ineffective position, will pivot the lever 400 about itspivotal point from the position of Figure 2, in which the knife isineffective, to the position of Figure 3, inpwhich the knife is active.The knife is normally ineffective, and can be rendered effective, owingto the construction of the treadlet313 and the treadle-rods 316 and 424,only when the feed point is down.

As illustrated and described in the said Letters Patent No. 1,527,396,friction clutch faces 7 0 and 72, Fig. 1, may be caused to engage moreor less firmly by suitable manipulation of a treadle 81, acting througha link 82 Y anda bell-crank lever 78, thus providing for varying thespeed of rotation of the driving shaft 66. According to the presentinvention, slowing down the speed of the machine in this mannerautomatically reduces the rate of feeding movement, so that curved partsof the materiallare fed through the machine not only at less speed, butby shorter feed strokes as well. This desired result is brought about,in the illustrative machine, by automatically adjusting the eccentricityof the eccentric 106 upon the end of the shaft 66, in accordancewiththevalue of the speed of rotation of the shaft 66, causing therocking support (shown in Letters Patent No. 1,527 ,396 at 94) thatcarries the feed elements 30 and 41 to-A` be rocked, through greater orless amplitudes of rocking movement, as the case may be. The saidrocking support may, indeed, be maintained absolutely stationary,preventing any feed movement at all, which is very desirable when verysharp concave or convex portions of the stock are encountered. Atsuchplaces the wiper, the fold presser and the other operatinginstrumentalities continue to operate while no feeding at all takesplace, theoperator simply turning the stockin its plane to permitsuccessive portions of the margin to become successively folded. Theoperation will be understood more particularly from- Figure 18, wherethe edge 26 of the binding strip is shown crowded a little by minutestages at 448. The crowding is of so minute a character', that forpractical purposes, the edge fold' is perfectly smooth, unmarred by anywrinkles or bunching whatsoever. The action of the diagonal pinchingedge 144 of the fold presser 42 materially contributes to the desiredresult; for asthe edge 144 extends rearward a substantial distanceacross the sharp convex edge of the material, the fold is therebypinched, not straight across, but at an angle to the strip. Feed controlof this character is believed to be produced herein for the first time,and is considered to be of far greater application than tobinding-stripfolding machines in particular, or shoe machines ingeneral. The specific construction employed will now be described.

The driving shaft 66 is shown more particularly in Figure 14, providedwith a longitudinal eccentric bearing 450 for a second shaft 452 uponthe forward end 454 of which the eccentric or crank stem 106 is carried.

The bearing 450 may be produced by longitudinally drilling through theshaft 66, or preferably, the shaft 66 may be made hollowr to start withand bushings 456 plugged into its ends. The bushings are eccentricallybored to provide the bear-ing 450. The space 458, between the bushings,may be utilized as an oil chamber. According to the actual constructionillustrated, but one bushing 456 is employed, at the rear end of theshaft, the forward end being shown solid. rlhe forward wall of the oilchamber 458 is indicated, in dotted lines, at 460. In whatever mannerthe structure is manufactured, it will be clear that, Vby rotatablyadjusting the shaft 452 within the bearing 450, the'eccentric or crankstem 106 may be made to assume different eccentric positions upon theforward end of the shaft 66. According as the crank stem is adjustednearer to or farther from the center of the shaft, the feed steps willbe shortened or lengthened. If the crank stem is caused toI assume aposition exactly central of the shaft, as illustrated in Figure 14, itwill remain exactly central throughout the rotation of the shaft, andthe shaft, will continueto rotate without rocking the said rockingsupport; and the feed elements willithereforc remain at rest. U Thelength of the feed strokes 1s automatll cally varied in accordance withthe variation centrifugally forced outward pivotally about the pivotalpoints 470, causing the gears 464 and 462 to rotate the shaft 452 withinits bearings 450. As the machine slows down, very stiff springs 472,each attached at one end 474 to the arms 468 and at the other end 47 6to a stationary part of the balance wheel 68, draw the governor weightsback toward normal position, correspondingly rotatably adjustlng theshaft 452. Any intermediate rate of feed between maximum and minimumvalues may be obtained by speeding the machine up more or less, asdesired, the variable centrifugal force acting upon the governor weights466 at different speeds being always balanced by the variable tension onthe springs 472 corresponding to those speeds.

To increase or decrease the normal .ten` sion on the springs, the ends476 are secured,

.not directly to the hand-and-balance wheel,

but to diametrically opposed points of a spring collar 47 8 that issplit at 480 to facilitate its mounting within an annular groove 482 ofthe hand-and-balance wheel 68. The

collar 478 is provided with gear teeth 484 that mesh with the teeth of apinion 486 that is secured, as by means ofl a pin 488, to a The pinion486 is provided with ratchet teeth 498 that engageratchet teeth 500 uponthe inner face of a block' 502 that is set in position within a recess504 upon the periphery of the hand-and-balance wheel. The plunger 490extends through an opening 506 of theblock 502 and its head is slottedat 508 to receive a screwdriver. When it is desired to adjust the normaltension of the springs 472, a screw driver is inserted in the slot 508,the plunger 490 is'forced inward by pressing in on the screw driver, inopposition to the force of the spring 496, 'thereby disengaging theratchet teeth 498 frpm the ratchet teeth 500. rllhe screw driver 1s thenturned to rotate the inion 486, in one direction, or the springs 47,2are permitted to eect rotation of the pinion in the opposite direction.Rotation of the pinion causes rotation of the split collar 47 8 in oneor the other direction. Releasing the screwV driver results in the M'plunger becoming spring-forced back into place, to cause the ratchetlteeth 498 and 500 to engage once more, locking the split collar inadjusted-position.

The limits of the rate offeed may be adjusted by slidably adjustablestops 510 and 512, the former adapted` to be engaged by one of thegovernor weights 466 to limit the outward movement of the governor, andthe latter by the other governor weight 466 to limit its inwardmovement. By. adjusting the stop 510, the maximum rate of feed maymounted in bearings 518 and 520.

minimum rate of feed. may bey controlled within any desired limitsbetween zero and any other desired minimum value. The stops 510and 512may be adjusted by rotating screw-threaded rods 514 that are'threadedthrough screw-threaded openings 516 of the stops. The screw-threadedrods 514 are 521 prevent longitudinal movement of the rods 514.

As will be understood from Figures 1 and 14, the gear 462 is heldagainst the bushing 456 by a button 522 that is screwed intothe forwardend of a short shaft 524 mounted inthe bearing collarl 526. For purposesof convenience in assembly, the bushing 456 and the shaft 524 areprovided with annular ianges 528 and 530, respectively, that are securedto each other andl to the hand-andbalance wheel 68 by screws 532.

Although the invention has been described.

above in connection with a special machine disclosed in theabove-identified Letters Patent No. 1,527 ,396, it will be understoodthat this is for illustrative purposes only, and that the 'invention isof broader scope, unlimited except in so far as limitations may bespecifically imposed in the. appended claims.

What is claimed as new is: 1. A machine for folding a strip aroun theedge of a sheet of material to one face of which, along the saidedge,'an edge of the strip is secured so that the sheet and the stripextend from the secured-together edges at an angle to each other, thesaid machine having, 1n combination, means for moving the unsecured edgeof the strip across the secured-together edges, lmeans for folding" thestrip'around the secured-together edges, a separator adapted to liebetween the strip and the secured-together edges, and a movable knifefor 'slitting the unsecured edge of the folded strip. the separatorconstituting a stationary knife for cooperating with the movable knifeto effect the slitting of thev 2. The method of snipping the margin of astrip of material that comprises clamping the strip at a point removedfrom the said margin, puncturing the unclamped margin at an interiorpoint with a sharp-pointed instrument, and swinging the instrumentoutward towards the edge of the strip to snip the margin from theinterior point outward to the edge.

3. A machine of the class described hav-l' ing, in combination, meansfor clamping a strip of material at a point removed from the lmarginthereof, a sharp-pointed knife,

and means for actuating the knife to punc- Collars of the strip to snipthe margin from the interior point to the edge.

4. A machine of the classdescribed having, in combination, feedingmeans, a shaft for actuating the same having a gear, a gear meshing withthe shaft gear, a knife, and a clutch for connecting the knife so as tobe i driven by the second-named gear.

5. A folding machine having, in combination, folding means, a knife, ashaft for actuating the folding means and the knife, and means foryautomatically disconnecting the knife from the shaft upon apredetermined degee of rotation of the shaft.

6. A machine vofthe class described having,

in combination, a pivotally mounted platform upon which material isadapted to rest, a knife and a lever for controlling the knife pivotallymounted about the pivotal point `of the platform.

. 7 A machine of the class described having, Y

in combination, aframe, a'retainer, an element against which theretainer is adapted to clamp material, means .for actuating the retainertowards and from the element to clamp and unclamp the material, theretainer having an arm adapted to engage the frame to prevent theretainer being actuated-into contact with the element when no materialis interposed between the retainer and the element, `and means wherebythe armk may be adjusted.

' 8. The method of folding 'a strip around the edge of a sheet ofmaterial to one face of which, along the said edge, an edge of the stripis secured so that the sheet and the struction in the direction of theline of fee'd i to cause a gradual folding of the strip around the saide ge of the sheet, and pressing the folded strip into contact with theother face of the sheet. 9. A machine of-the'class described having, 1ncombination, feeding means comprising a normally effective feed point,normally ineffective cuttin means, a treadle connected to the feed pointand the cutting means, and means whereby the treadle is adaptedselectively tomender the feed point ineffective andv the cutting meanseffective.

1Q. 'A folding machine having, in combinat1on, a support, a wipermounted on th'e support, a retainer cooperating with thewiper having anarm adapted to rest upon the support, means .whereby the support may beadjusted and means lwhereby the arm may be adjusts ing, combination, asupport, a feed point, a retamer having an arm adapted to rest upon thesupport, means for moving the feedpoint,

11. Amachine of the class described havi and means wherebymovement ofthe feed point effects movement of the arm fromoff1 the support.

12. A machine for folding the margins of sheet material having sharpconvex edges having, in combination, a feed block and a feed point forfeeding the material, a plow for folding the margin of the material, anda fold presser for pressing the folded margin, the fold presser having adiagonal edge eX- tending rearward a substantial distance across thesharp convex edges, and the feed point having a face correspondingly cutaway diagonally, the feed point being adapted to be moved forwardtowards the fold presser y so that its diagonal faceshall be very closeto the diagonal7 ed e of the fold. presser.

13. A machine or folding a strip around the edge of a sheet of materialto one face of which, along the said edge, an edge of the strip issecured so that the-sheet and the strip extend from the securedtogetheredges at an angle to eachother, the said machine having iny combination,a wiper for wiping the'strip tightly across the securedtogether edges, alow for initially folding the strip around t e secured-together edgesafter it has been wiped, the plow having a diagonally cut-away portion,a separator adapted to lie betweenl the strip and the secured-togetheredges near the cut-away portion, and afold presser for pressing theinitially folded strip into even contact with the other face of thesheet.

14. A machine of the-class described having, in combination, a frame,means for feeding material step by step, a retainer,an element againstwhich the retainer is adapted to clamp material, and means for actuatingthe retainer towards and from the element to clamp the material duringpauses in' thev feed and to unolamp the material, the retainer having anarm adapted to engage the frame to prevent the retainer from beingactuated into contact with the element when no material is interposedbetween the retainer and the element. v

15. A machine for folding a strip around l the edge of a sheet ofmaterial to one face of which, along the said edge, an edge of the stripis secured so that the sheet and the strip extend fromy thesecured-together edges at an angle to each other, the said machinehaving, in combination, means forv feeding the sheet and the strip, aplow for folding the strip around the secured-together edges,

lthe plow being of gradual incline construction in the direction of theline of feed to eEect a gradual folding of the strip around the saidedge of the sheet, and a fold presser for pressing the folded strip intocontact with the otherface of the sheet.

16. rfhe method offolding the margin of f ing the material in its planeand holding it against feeding movement while folding the curvedportions of the margin, and feeding the material while folding otherportions of the margin.

17. A flding machine having, in combination, a fold presser, means forfeeding sheet material the edge of which is sharply curved to the foldpresser and means operable during the operation of the machine forcontrolling the feeding means to hold the material against feedingmovement while permitting turning of the material in its plane duringthe action of the fold presser upon sharply curved portions of themargin, the fold presser and the feeding means being situated close toeach other to permit the fold presser to act upon the sharply curvedportions of the margin, while the material is turned in its planewithout being fed.

18. A folding machine having, in combination, means for folding sheetmaterial, means for feeding material to thefolding means by step-by-stepfeed strokes, means for controlling the speed of the feeding means, andmeans for varying the lengths of the feed strokes' in accordance withthe speed of operation of the feeding means.

19. A folding machine having, in combination, means for folding sheetmaterial, means for feeding the material to the folding means, and meanscontrolled in accordance with the speed of operation of the feedingmeans for varying the rate of feed of the feeding means.

20. A method of folding sheet material that comprises feeding thematerial by stepby-step feed strokes, folding the materialat apredetermined point in the path of feed, varying the speed of thefeed-ofthe material, and varying the lengths of the feed trfkes in accordancewith the speed of the 21. A method of folding sheet material thatcomprises feeding the material, folding the material at a predeterminedpoint in the path of feed, varying the speed of the feed of thematerial, and varying the rate of the feed of the material in accordancewith the speed of the feed.

ln testimony whereof, l have hereunto subscribed my name this 9th day ofJune, 1921..

AREW R. RIDDERSTROM.

a sheet of material the edge of which is variously curved, said methodcomprising turn-

